reverberation amp  ('77-'82)  $150

In very good cosmetic condition and fully operational, this totally retro Sansui RA-500 spring reverb amp has been opened up, checked, cleaned and tested.  

When powered up and connected (through the tape in & out loops of any stereo receiver), the front display comes alive with twin "oscilloscope" spring rainbows of color that provide a visual depending on choice of reverb intensity. 

Besides the power button, the other two front panel controls are extremely simple.  One adjusts the "spread" of the reverberation and the other selector turns the reverb signal on or off.The real walnut case has been lightly sanded and refinished. 

The Sansui RA-500 is the perfect accessory add-on for any vintage stereo system.

The best layman's explanation of the RA-500 operation: 
"The reverberation output is a summation of the *dry / wet signals (see "History" below).  The reverb tank takes a mono sum of the stereo input and feeds that to two springs in the tank.  Because of the two separate springs, the reverb has a nice spread to it.  Technically, while it's not a true stereo reverb, your ears will not notice because of the easily adjustable spread."

About reverberation amplifiers...
One of the earliest reverb units was the Fisher K-10 SpaceXpander which was a spring tube reverb unit from the 60's. Legend has it that the K10 was used in car audio and Hammond organs.  Technically, reverberation is just an echo of a sound which reaches the listeners ear a fraction of a second after the sound from the original source is heard.  

A product of acoustics, natural reverb has been an important component of music for centuries. Concert halls were (and still are) specifically designed to control the propagation of reverberant signals in the room. This is done to redirect sound waves to the audience, creating a lush ambience in which the music occurs and is experienced.

Natural reverb in music is simply achieved by recording in a reverberant space, a space which creates room noise that’s captured in the recording.

Because the reverb must be captured in the recording process, studios invested in custom-built recording rooms to achieve the sound that they were after. Famous spaces like the main recording room in Columbia Records’ 30th Street Studio in New York (nicknamed "The Church"), renowned for their reverberant signatures, were utilized as the reverb source for some of the most famous projects in music (the legendary 1959 "Kind of Blue" album from Miles Davis was recorded at 30th Street).

In a natural reverb context, the *dry / wet balance is determined by the distance between the microphone and the sound source. By playing close to the microphone, the dry signal is relatively louder than the room noise, leading to a dryer recording.  Playing further from the microphone causes direct sound from the sound source to blend with the room noise. With the room playing a larger role in determining which sound waves reach the microphone, a wetter sound is created.

If you're more interested in the WHOLE story of reverb history, go here:
https://www.izotope.com/en/learn/a-history-of-reverb-in-music-production.html#:~:text=The%20first%20of%20these%20systems,effect%20to%20replicate%20this%20reverb.

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integrated amp ('72-'74) 30 WPC @ 8 ohms / 44 WPC @ 4 ohms   $500
(wood case & vu meters available as options at additional cost)

In excellent cosmetic and working condition, this Sansui AU-6500 pre-main amp has been fully serviced; all inputs, outputs and functions are performing perfectly. 

Although it's rated at a very conservative 30 watts per channel into 8 ohms and 44 watts per channel into 4 ohms, it has headroom way beyond those ratings.  Essentially, the AU-6500 offers a very substantial performance with all the functions necessary for most that demand Sansui's legendary build quality. 

The easily recognizable design of these Sansui units are its black satin faceplate with a chrome frame, knurled metal knobs (with polished silver edge) and large switch controls.  The controls are loudness, muting circuit and low / high filter.  Each knob and switch feels solid which is typical of a higher end design.  Only one lamp indicates power on that switches from red to green when it's ready to go.  Rear jumpers allow the 6500 to be used as either a preamp OR amp.  Notably, among all the usual inputs and outputs, there are outputs for two turntables.

Tech info:
The power amp section is a pure complimentary service circuit directly connected to all stages by symmetrically combining PNP-NPN power transistors that results in very low distortion.
The power supply is equipped with a large transformer and 6,800 μ Fx2 capacitor.
The equalizer circuit uses a combination of low-noise transistors and PNP-NPN-PNP to achieve low noise and wide dynamic range.  The protective circuit is a combination of a transistor, a diode and a relay, and is also equipped with a short-cut fuse to ensure safety.

Specs:
Power output: 30 watts per channel into 8Ω (stereo)
Frequency response: 10Hz to 30kHz: 0.1%
Damping factor: 40
Input sensitivity: 2.5mV (MM), 100mV (DIN), 100mV (line)
Signal to noise ratio: 70dB (MM), 80dB (line)
Output: 100mV (line), 30mV (DIN), 0.8V (Pre out)
Speaker load impedance: 4Ω to 16Ω
Dimensions: 17.3"W x 5.5"H x 12.6"D
Weight: 26 lbs

About Sansui...
The name Sansui is translated as meaning "mountain and water".  Founded in Tokyo in 1947, Sansui initially manufactured electronic parts.  By the 1960s, they had developed a reputation for making serious audio components. They were sold in foreign markets through that and the next decade.  Sansui's amplifiers, receivers, speakers turntables and tuners from the late 60's, through the 70's and very early 80's continue to remain in high demand by audio enthusiasts.

Note: Sansui Electric Co., Ltd. is now part of Grande Holdings, a Chinese Hong Kong-based conglomerate, which also owns Japanese brands Akai and Nakamichi. The name still appears on modern budget hi-fi separates in some markets, but doesn’t share any real DNA with the AU-6500. If you want to know how great it once was, then check out one of these 70's lovelies; they’re far cheaper than you’d expect for such a well built and sonically capable product; mint examples like these are a great addition to any collection of fine vintage stereo collections.

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('79-'80)  16 WPC  $225

This late 70's Realistic STA-52B stereo receiver from Realistic (Tandy) is an excellent quality piece, built to a standard, not a price. It has been completely serviced and polished inside and out so it once again looks and performs beautifully.   All new lamps have been installed.

The STA-52B is very similar in looks to the earlier STA-52 except the "B" has the ability to drive two pairs of efficient speakers (the earlier STA-52 only allowed for one pair).

This "little" receiver easily outperforms many modern day products all these years later. It delivers an honest 16 watts per channel RMS into 8 ohms (a little more into 4 ohms), can run two speaker zones, and has an auxiliary input (suitable for streaming), a tape input (or 2nd aux), and a phono input. All of the expected features such as tone controls and loudness compensation are present. 

The inbuilt stereo tuner is sensitive, wide bandwidth, and low distortion. It features the signature color change dial pointer that changes from amber to red on a tuned stereo station. Pretty cool!

It’s a handsome looking vintage piece as well with its wide backlit dial scale, Pioneer style lever switches and the brushed silver escutcheon contrasts beautifully with the real walnut veneer over ttimberwood cabinet.

Main specs:
Power output: 16 watts RMS per channel into 8Ω (stereo)
Frequency response: 20Hz to 30kHz
Speaker load impedance: 4Ω to 16Ω
Dimensions: 17.5"W x 6"H x 12"

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('80-'81)  120 WPC (180 WPC @ 4)  SOLD

Rare, powerful, in excellent cosmetic condition and fully operational, this Concept 12.0D receiver can be counted on to anchor practically any stereo system you can imagine.

Wrangling this beast around on the bench for servicing is always trippy.  Looking at that massive toroidal transformer is jaw dropping indeed!  The wiring and board layout is also impressive but, sometimes, just getting to the backside of the individual pushbuttons for some deoxit and cleaning can be a challenge.  Patience is required.

Even though there's not much interest in listening to the radio these days, the Concept 12.0D actually makes it fun again,  The tuner is a marvel in itself.  They went above and beyond just dropping a tuner into the box; it's a very high quality and inventive digital synthesized section of the receiver.

From Concept:
"The 12.0D delivers a standard of accuracy unmarred by audible distortion. This was achieved by selecting only the best of the premium quality parts available at the time that would manage to continuously operate far below their capabilities.  

The 12.0D continued the Concept tradition of stereo receivers without compromise.  Every detail, from the action of the controls to the size of the internal heat sinks, was carefully crafted by a distinguished international team of designers and production engineers.

While all of the previous analog Concept models were outstanding to begin with, there are a number of design innovations that make this elusive Concept 12.0D a truly remarkable instrument.  It effortlessly pumps out a minimum of 120 watts per channel @ 8 ohms and a whopping 180 watts per channel @ 4 ohm loads. 

The power amplifier section uses a high gain voltage amplification followed by rugged output transistors in a carefully stabilized, high speed configuration. The huge toroidal power transformer efficiently supplies power for the most demanding musical passages. The result is a unit that can amplify rapidly changing audio signals while producing the lowest possible distortion.

The 12.0D features all electronic tuning with a quartz crystal reference that makes precise tuning as simple as the touch of a button. Electronic memories store up to six stations for instant access.  As long as the receiver is plugged in, all memories are kept locked in, even for the digital clock which stays on when the unit is turned off although it can be switched off if desired."

With the Concept trademark rosewood veneer case and weighing in at 51 lbs, the 12.0D features outputs for three pairs of speakers and two tape/aux and a flexible tone/equalizer array for mid-bass/treble.  It also has a unique, continuously variable loudness control instead of the usual on/off switch.

Finally, the whole idea of the Concept design was to build them well enough so that the result would be consistent performance for many years of trouble free service...they succeeded.  A copy of the owner's manual is included.

Basic specs:
Power output: 120 watts per channel into 4 ohms
                        180 WPC into 4 ohms
Frequency response: 20Hz to 20kHz
THD: 0.02%
Dimensions: 21"W x 7.5"H x 17"D
Weight: 51 lbs

About Concept...
Recognized universally as some of the very best stereo receivers ever made, the Concept receivers circuitry was designed in-house, by Dick Schram, at Pacific Stereo (late 70's California). Tom Ishimoto, former product development manager of Marantz, also had a hand in building some of the Concept line at NEC of Japan.

The bulk of the manufacturing was done by TCE, an electronics manufacturing division of Tandy Corp. (Tandy was the parent company of U.S. electronics retail chain Radio Shack). A lot of effort was made in upgrading the Concept design capabilities, and TCE's production techniques at the time were described as "terrific". Several other manufacturers were considered for the Concept receivers, but, as far as Schram was concerned, TCE was by far the best. They had gifted engineers who were excited to work on some REAL hi-fidelity audio products and became very loyal to him during the entire process.

The Concept credo was "better quality parts, operated with more margin of safety, superior circuits and no shortcuts" - that's why they last so long and still sound as good today.

More about Pacific Stereo (and Concept...)
The Concept line of stereo receivers were offered by Pacific Stereo as their top tier house brands. (in order, top to bottom: Concept, Reference by Quadraflex, Quadraflex and TransAudio) The top of the line was the Concept 16.5 (165 watts per channel, considered by many to be the best stereo receiver ever made!). 

Basically, when a customer went into a Pacific Stereo store looking for Pioneer, Sansui, Kenwood, etc, the salesman would steer them toward one of the "house" brands, the best of which were the Concepts.  Normally you might think that the house brand would be some cheaply made unit designed for maximum profit to the retailer. But, in this case, the Concepts (and secondarily, the Reference series) were very well built and high performing receivers.  Especially the Reference 650FETR which was Richard Schram's baby all the way, a very fine stereo receiver that deserves to be in any serious audiophile's collection.

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